The invention relates to a device for aerobic microbiological treatment of waste water by producing a biodispersion.
Aerobically living microorganisms have to be supplied with oxygen dissolved in water, so that they can convert and mineralise the xe2x80x9cdirt sourcesxe2x80x9d present in the waste water by respiration. When there is a rich supply of convertible water contents and adequately dissolved oxygen in the waste water, microbiological respiration takes place as so-called xe2x80x9cmultiplication respirationxe2x80x9d, wherein microorganisms multiply by division and therefore can breakdown the rich supply. When the supply is low, the microorganisms switch to xe2x80x9clife-support respirationxe2x80x9d, in which only low conversion is carried out.
According to the state of the art, technologies are used which result in multiplication respiration, since high breakdown capacities should be achieved in the reactors. However, this multiplication respiration brings with it the main technological problem of waste water purification, which lies in the fact that considerable sewage sludge is produced which can only be disposed of very expensively.
The object of the invention is therefore to provide a device for aerobic microbiological treatment of waste water, in which only comparatively little sewage sludge is produced, wherein at the same time good efficiency is retained and purified water of good quality is achieved and wherein a simple construction of the device should be guaranteed, which can be adapted to different quantities of waste water.
This object is achieved according to the invention by the features of the independent claim.
Due to the fact that the device of the invention has a filter and aeration unit arranged in the lower part of the reactor, which consists of porous hollow bodies arranged one above another and serving as membranes, a bio-membrane reactor is made available, which reduces the sewage sludge problem in that the microorganisms are held back in the bio-membrane reactor by microfiltration and the respiration stress for the microorganisms resulting therefrom, caused by the fact that indeed sufficient oxygen is available, but the C source is not adequate, so that they have to be economical with the metabolism, leads to life-support respiration. Life-support respiration indeed causes a lower metabolism, but this is made up for again by the higher microbiological density, so that overall a breakdown capacity per m2 of reactor is achieved as for multiplication respiration. The microorganisms and water contents penetrating into the pores of the porous membranes during rnicrofiltration are rinsed out again during aeration, which takes place spasmodically, so that very long membrane service lives are possible. The porous hollow bodies, which in each case serve as a membrane, are used in both directions due to the alternating aeration and microfiltration process.
In addition to reducing the biomass, that is the sewage sludge, the waste water is treated by microfiltration, so that it satisfies the legal requirements for irrigation on site and for direct introduction, as a result of which decentralised waste water purification may be provided and the water cycle may be closed particularly in rural communities.
Specific and economic oxygen introduction is possible at any point over the cross-section due to the porous hollow bodies arranged one above another and serving as a membrane, the micropores of which are distributed uniformly over the cross-section of the reactor, so that there is no undersupply of oxygen and the microorganisms remain alive. After microfiltration, purified water is achieved of a quality which facilitates re-use in the production of non-drinkable water etc.
Advantageous further developments and improvements are possible due to the measures indicated in the sub-claims. It is particularly advantageous that when providing either several reactors or at least two filter and aeration units, which alternately aerate and filter, a continuous operation is possible.
The required preliminary pressure for microfiltration may be adjusted and the reactor residence time of the waste water determined by the control of the aeration process, but not by the signals of the oxygen measuring device and the pressure measuring device in the reactor collection chamber.